#include <memory.h>
#include <stdio.h>
#include "fun_md5.h"

#define MD5_SIZE        16
#define MD5_STR_LEN        (MD5_SIZE * 2)

typedef struct
{
    unsigned int count[2];
    unsigned int state[4];
    unsigned char buffer[64];   
} MD5_CTX;

#define F(x,y,z) ((x & y) | (~x & z))
#define G(x,y,z) ((x & z) | (y & ~z))
#define H(x,y,z) (x^y^z)
#define I(x,y,z) (y ^ (x | ~z))
#define ROTATE_LEFT(x,n) ((x << n) | (x >> (32-n)))

#define FF(a,b,c,d,x,s,ac) \
{ \
    a += F(b,c,d) + x + ac; \
    a = ROTATE_LEFT(a,s); \
    a += b; \
}
#define GG(a,b,c,d,x,s,ac) \
{ \
    a += G(b,c,d) + x + ac; \
    a = ROTATE_LEFT(a,s); \
    a += b; \
}
#define HH(a,b,c,d,x,s,ac) \
{ \
    a += H(b,c,d) + x + ac; \
    a = ROTATE_LEFT(a,s); \
    a += b; \
}
#define II(a,b,c,d,x,s,ac) \
{ \
    a += I(b,c,d) + x + ac; \
    a = ROTATE_LEFT(a,s); \
    a += b; \
}       

#define MAXREADFILEDATALENGTH  50000//1024*1024  //1M

static unsigned char PADDING[] =
{
    0x80,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
};

/*MD5 init*/ 
static void MD5Init(MD5_CTX *context)
{
    context->count[0] = 0;
    context->count[1] = 0;
    context->state[0] = 0x67452301;
    context->state[1] = 0xEFCDAB89;
    context->state[2] = 0x98BADCFE;
    context->state[3] = 0x10325476;
}
 
static void MD5Decode(unsigned int *output, unsigned char *input, unsigned int len)
{
    unsigned int i = 0;
    unsigned int j = 0;

    while(j < len)
    {
    output[i] = (input[j]) |
        (input[j+1] << 8) |
        (input[j+2] << 16) |
        (input[j+3] << 24);
    i++;
    j += 4; 
    }
}

static void MD5Transform(unsigned int state[4], unsigned char block[64])
{
    unsigned int a = state[0];
    unsigned int b = state[1];
    unsigned int c = state[2];
    unsigned int d = state[3];
    unsigned int x[64];

    MD5Decode(x,block,64);

    FF(a, b, c, d, x[ 0], 7, 0xd76aa478); /* 1 */
    FF(d, a, b, c, x[ 1], 12, 0xe8c7b756); /* 2 */
    FF(c, d, a, b, x[ 2], 17, 0x242070db); /* 3 */
    FF(b, c, d, a, x[ 3], 22, 0xc1bdceee); /* 4 */
    FF(a, b, c, d, x[ 4], 7, 0xf57c0faf); /* 5 */
    FF(d, a, b, c, x[ 5], 12, 0x4787c62a); /* 6 */
    FF(c, d, a, b, x[ 6], 17, 0xa8304613); /* 7 */
    FF(b, c, d, a, x[ 7], 22, 0xfd469501); /* 8 */
    FF(a, b, c, d, x[ 8], 7, 0x698098d8); /* 9 */
    FF(d, a, b, c, x[ 9], 12, 0x8b44f7af); /* 10 */
    FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
    FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
    FF(a, b, c, d, x[12], 7, 0x6b901122); /* 13 */
    FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
    FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
    FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */

    /* Round 2 */
    GG(a, b, c, d, x[ 1], 5, 0xf61e2562); /* 17 */
    GG(d, a, b, c, x[ 6], 9, 0xc040b340); /* 18 */
    GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
    GG(b, c, d, a, x[ 0], 20, 0xe9b6c7aa); /* 20 */
    GG(a, b, c, d, x[ 5], 5, 0xd62f105d); /* 21 */
    GG(d, a, b, c, x[10], 9,  0x2441453); /* 22 */
    GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
    GG(b, c, d, a, x[ 4], 20, 0xe7d3fbc8); /* 24 */
    GG(a, b, c, d, x[ 9], 5, 0x21e1cde6); /* 25 */
    GG(d, a, b, c, x[14], 9, 0xc33707d6); /* 26 */
    GG(c, d, a, b, x[ 3], 14, 0xf4d50d87); /* 27 */
    GG(b, c, d, a, x[ 8], 20, 0x455a14ed); /* 28 */
    GG(a, b, c, d, x[13], 5, 0xa9e3e905); /* 29 */
    GG(d, a, b, c, x[ 2], 9, 0xfcefa3f8); /* 30 */
    GG(c, d, a, b, x[ 7], 14, 0x676f02d9); /* 31 */
    GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */

    /* Round 3 */
    HH(a, b, c, d, x[ 5], 4, 0xfffa3942); /* 33 */
    HH(d, a, b, c, x[ 8], 11, 0x8771f681); /* 34 */
    HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
    HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
    HH(a, b, c, d, x[ 1], 4, 0xa4beea44); /* 37 */
    HH(d, a, b, c, x[ 4], 11, 0x4bdecfa9); /* 38 */
    HH(c, d, a, b, x[ 7], 16, 0xf6bb4b60); /* 39 */
    HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
    HH(a, b, c, d, x[13], 4, 0x289b7ec6); /* 41 */
    HH(d, a, b, c, x[ 0], 11, 0xeaa127fa); /* 42 */
    HH(c, d, a, b, x[ 3], 16, 0xd4ef3085); /* 43 */
    HH(b, c, d, a, x[ 6], 23,  0x4881d05); /* 44 */
    HH(a, b, c, d, x[ 9], 4, 0xd9d4d039); /* 45 */
    HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
    HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
    HH(b, c, d, a, x[ 2], 23, 0xc4ac5665); /* 48 */

    /* Round 4 */
    II(a, b, c, d, x[ 0], 6, 0xf4292244); /* 49 */
    II(d, a, b, c, x[ 7], 10, 0x432aff97); /* 50 */
    II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
    II(b, c, d, a, x[ 5], 21, 0xfc93a039); /* 52 */
    II(a, b, c, d, x[12], 6, 0x655b59c3); /* 53 */
    II(d, a, b, c, x[ 3], 10, 0x8f0ccc92); /* 54 */
    II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
    II(b, c, d, a, x[ 1], 21, 0x85845dd1); /* 56 */
    II(a, b, c, d, x[ 8], 6, 0x6fa87e4f); /* 57 */
    II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
    II(c, d, a, b, x[ 6], 15, 0xa3014314); /* 59 */
    II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
    II(a, b, c, d, x[ 4], 6, 0xf7537e82); /* 61 */
    II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
    II(c, d, a, b, x[ 2], 15, 0x2ad7d2bb); /* 63 */
    II(b, c, d, a, x[ 9], 21, 0xeb86d391); /* 64 */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}


static void MD5Update(MD5_CTX *context, unsigned char *input, unsigned long inputlen)
{
    unsigned int i = 0;
    unsigned int index = 0;
    unsigned int partlen = 0;

    index = (context->count[0] >> 3) & 0x3F;
    partlen = 64 - index;

    context->count[0] += inputlen << 3;
    if(context->count[0] < (inputlen << 3))
    context->count[1]++;
    context->count[1] += inputlen >> 29;

    if(inputlen >= partlen)
    {
    memcpy(&context->buffer[index], input,partlen);
    MD5Transform(context->state, context->buffer);

    for(i = partlen; i+64 <= inputlen; i+=64)
        MD5Transform(context->state, &input[i]);
    index = 0;        
    }  
    else
    {
    i = 0;
    }
    memcpy(&context->buffer[index], &input[i], inputlen-i);
}
 
static void MD5Encode(unsigned char *output,unsigned int *input,unsigned int len)
{
    unsigned int i = 0;
    unsigned int j = 0;

    while(j < len)
    {
    output[j] = input[i] & 0xFF;  
    output[j+1] = (input[i] >> 8) & 0xFF;
    output[j+2] = (input[i] >> 16) & 0xFF;
    output[j+3] = (input[i] >> 24) & 0xFF;
    i++;
    j += 4;
    }
}

static void MD5Final(MD5_CTX *context, unsigned char digest[16])
{
    unsigned int index = 0,padlen = 0;
    unsigned char bits[8];

    index = (context->count[0] >> 3) & 0x3F;
    padlen = (index < 56)?(56-index):(120-index);
    MD5Encode(bits, context->count, 8);
    MD5Update(context, PADDING, padlen);
    MD5Update(context, bits, 8);
    MD5Encode(digest, context->state, 16);
}

/******************************************************
187 *函数名称:Compute_data_md5
188 *输   入:data 校验数据首地址
189         len 校验数据长度
190         md5_str 字符串形式的MD5值
191 *输   出:无
192 *功   能:计算数据MD5值，并以字符串形式返回
193 *******************************************************/
static int Compute_data_md5(unsigned char *data, unsigned long len,unsigned char *md5_str)
{
    unsigned char md5_value[MD5_SIZE];
    unsigned int i = 0;

    MD5_CTX md5;

    MD5Init(&md5);
    MD5Update(&md5, data, len);
    MD5Final(&md5, md5_value);
    for(i = 0; i < MD5_SIZE; i++)
    {
    snprintf((char*)md5_str + i*2, 2+1, "%02x", md5_value[i]);
    }
    md5_str[MD5_STR_LEN] = '\0'; // add end
    return 0;
}

static int FileDataMd5(const char *path,unsigned char *md5_str)
{
    long fileSize=0;
    //unsigned char md5_str[100] = {0};
    if((path == NULL)||(md5_str == NULL)) return -1;
    FILE * fd = fopen(path, "r");
    if(fd == NULL) return -1;

    if(fseek(fd, 0L,SEEK_END) < 0)
    {
    fclose(fd);
    }
    fileSize = ftell(fd);
    fseek(fd, 0L,SEEK_SET);
    //printf("filesize = %ld\n",fileSize);

    long readLength = 0;
    int readCount = 0;
    if(fileSize <= MAXREADFILEDATALENGTH)
    {
    readLength = fileSize;
    readCount = 1;
    }
    else
    {
    readLength = MAXREADFILEDATALENGTH;
    if((fileSize % MAXREADFILEDATALENGTH) > 0)
        readCount = (fileSize / MAXREADFILEDATALENGTH) + 1;
    else
        readCount = fileSize / MAXREADFILEDATALENGTH; 
    }

    //printf("readcount = %d\n",readCount);

    unsigned char readBuff[readLength];
    memset(readBuff,0,readLength);

    int i=0;

    if(readCount == 1)
    {
        size_t ret = fread(readBuff, 1, readLength, fd);
        if(ret <= 0) return -1;
        //printf("ret = %d\n",ret);
        Compute_data_md5(readBuff,ret,md5_str);
    }
    else
    {
        unsigned char md5_value[MD5_SIZE];
        size_t ret;
        MD5_CTX md5;  
        MD5Init(&md5);

        for(i=0;i<readCount;i++)
        {
            fseek(fd,i*MAXREADFILEDATALENGTH,SEEK_SET);
            ret = fread(readBuff, 1, readLength, fd);
            if(ret <= 0) return -1;
            MD5Update(&md5, readBuff, ret);
            memset(readBuff,0,readLength);
        }
        MD5Final(&md5, md5_value);
        for(i = 0; i < MD5_SIZE; i++)
        {
            snprintf((char*)md5_str + i*2, 2+1, "%02x", md5_value[i]);
        }
        md5_str[MD5_STR_LEN] = '\0'; // add end
    }

    //printf("md5value = %s\n",md5_str);
    fclose(fd);
    return 0;
}


/**
 * @brief   计算MD5值
 * @param   inData: 需要计算的内容
 * @param   len:    内容的长度
 * @param   md5Str: 生成的MD5值（字符串）
 * @return  成功返回0，其他失败
 * @note    md5Str的空间至少需要33个字节
 * @date    2023-3-22
 * @author  Yin
*/
int fun_MD5Calculate(unsigned char *inData, unsigned long len,unsigned char *md5Str)
{
    if(!inData || !md5Str) return -1;
    return Compute_data_md5(inData,len,md5Str);
}


/**
 * @brief   计算文件的MD5值
 * @param   filePath: 文件路径
 * @param   md5Str:   生成的MD5值（字符串）
 * @return  成功返回0，其他失败
 * @note    md5Str的空间至少需要33个字节
 * @date    2023-3-22
 * @author  Yin
*/
int fun_MD5CalculateFile(char *filePath, unsigned char *md5Str)
{
    if(!filePath || !strlen(filePath) || !md5Str) return -1;
    return FileDataMd5(filePath,md5Str);
}


#ifdef MODULEDEMOTEST
#include <stdio.h>
static void MD5Demo()
{
    char md5_data[33];
    char *inData = "this is demo to test MD5";
    int ret;

    ret = fun_MD5Calculate((unsigned char*)inData,strlen(inData),(unsigned char*)md5_data);
    if(ret){
        printf("MD5 calculate fail\n");
        return;
    }
    printf("%s => %s\n",inData,md5_data);

    ret = fun_MD5CalculateFile("./fun_md5.c",(unsigned char*)md5_data);
    if(ret){
        printf("MD5 calculate file fail\n");
        return;
    }
    printf("./SD_MD5Module.c => %s\n",md5_data);
}

int main(int argc ,char** argv)
{
    MD5Demo();
    return 0;
}

#endif
